diff --git a/pkg/compiler/codegen.go b/pkg/compiler/codegen.go
index 0a976b73f..5be47dc70 100644
--- a/pkg/compiler/codegen.go
+++ b/pkg/compiler/codegen.go
@@ -14,6 +14,7 @@ import (
 
 	"github.com/nspcc-dev/neo-go/pkg/encoding/address"
 	"github.com/nspcc-dev/neo-go/pkg/io"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
 	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
 	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
@@ -746,12 +747,27 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 		return nil
 
 	case *ast.CompositeLit:
-		switch typ := c.typeOf(n).Underlying().(type) {
+		t := c.typeOf(n)
+		switch typ := t.Underlying().(type) {
 		case *types.Struct:
 			c.convertStruct(n, false)
 		case *types.Map:
 			c.convertMap(n)
 		default:
+			if tn, ok := t.(*types.Named); ok && isInteropPath(tn.String()) {
+				st, _ := scAndVMInteropTypeFromExpr(tn)
+				expectedLen := -1
+				switch st {
+				case smartcontract.Hash160Type:
+					expectedLen = 20
+				case smartcontract.Hash256Type:
+					expectedLen = 32
+				}
+				if expectedLen != -1 && expectedLen != len(n.Elts) {
+					c.prog.Err = fmt.Errorf("%s type must have size %d", tn.Obj().Name(), expectedLen)
+					return nil
+				}
+			}
 			ln := len(n.Elts)
 			// ByteArrays needs a different approach than normal arrays.
 			if isByteSlice(typ) {
diff --git a/pkg/compiler/debug.go b/pkg/compiler/debug.go
index 1676a0a3e..d82fc688e 100644
--- a/pkg/compiler/debug.go
+++ b/pkg/compiler/debug.go
@@ -228,6 +228,29 @@ func (c *codegen) scAndVMReturnTypeFromScope(scope *funcScope) (smartcontract.Pa
 	}
 }
 
+func scAndVMInteropTypeFromExpr(named *types.Named) (smartcontract.ParamType, stackitem.Type) {
+	name := named.Obj().Name()
+	pkg := named.Obj().Pkg().Name()
+	switch pkg {
+	case "blockchain", "contract":
+		return smartcontract.ArrayType, stackitem.ArrayT // Block, Transaction, Contract
+	case "interop":
+		if name != "Interface" {
+			switch name {
+			case "Hash160":
+				return smartcontract.Hash160Type, stackitem.ByteArrayT
+			case "Hash256":
+				return smartcontract.Hash256Type, stackitem.ByteArrayT
+			case "PublicKey":
+				return smartcontract.PublicKeyType, stackitem.ByteArrayT
+			case "Signature":
+				return smartcontract.SignatureType, stackitem.ByteArrayT
+			}
+		}
+	}
+	return smartcontract.InteropInterfaceType, stackitem.InteropT
+}
+
 func (c *codegen) scAndVMTypeFromExpr(typ ast.Expr) (smartcontract.ParamType, stackitem.Type) {
 	t := c.typeOf(typ)
 	if c.typeOf(typ) == nil {
@@ -235,26 +258,7 @@ func (c *codegen) scAndVMTypeFromExpr(typ ast.Expr) (smartcontract.ParamType, st
 	}
 	if named, ok := t.(*types.Named); ok {
 		if isInteropPath(named.String()) {
-			name := named.Obj().Name()
-			pkg := named.Obj().Pkg().Name()
-			switch pkg {
-			case "blockchain", "contract":
-				return smartcontract.ArrayType, stackitem.ArrayT // Block, Transaction, Contract
-			case "interop":
-				if name != "Interface" {
-					switch name {
-					case "Hash160":
-						return smartcontract.Hash160Type, stackitem.ByteArrayT
-					case "Hash256":
-						return smartcontract.Hash256Type, stackitem.ByteArrayT
-					case "PublicKey":
-						return smartcontract.PublicKeyType, stackitem.ByteArrayT
-					case "Signature":
-						return smartcontract.SignatureType, stackitem.ByteArrayT
-					}
-				}
-			}
-			return smartcontract.InteropInterfaceType, stackitem.InteropT
+			return scAndVMInteropTypeFromExpr(named)
 		}
 	}
 	switch t := t.Underlying().(type) {
diff --git a/pkg/compiler/interop_test.go b/pkg/compiler/interop_test.go
index dfdf7e8f6..6aa603aaa 100644
--- a/pkg/compiler/interop_test.go
+++ b/pkg/compiler/interop_test.go
@@ -24,6 +24,42 @@ import (
 	"go.uber.org/zap/zaptest"
 )
 
+func TestTypeConstantSize(t *testing.T) {
+	src := `package foo
+	import "github.com/nspcc-dev/neo-go/pkg/interop"
+	var a %T // type declaration is always ok
+	func Main() interface{} {
+		return %#v
+	}`
+
+	t.Run("Hash160", func(t *testing.T) {
+		t.Run("good", func(t *testing.T) {
+			a := make(cinterop.Hash160, 20)
+			src := fmt.Sprintf(src, a, a)
+			eval(t, src, []byte(a))
+		})
+		t.Run("bad", func(t *testing.T) {
+			a := make(cinterop.Hash160, 19)
+			src := fmt.Sprintf(src, a, a)
+			_, err := compiler.Compile("foo.go", strings.NewReader(src))
+			require.Error(t, err)
+		})
+	})
+	t.Run("Hash256", func(t *testing.T) {
+		t.Run("good", func(t *testing.T) {
+			a := make(cinterop.Hash256, 32)
+			src := fmt.Sprintf(src, a, a)
+			eval(t, src, []byte(a))
+		})
+		t.Run("bad", func(t *testing.T) {
+			a := make(cinterop.Hash256, 31)
+			src := fmt.Sprintf(src, a, a)
+			_, err := compiler.Compile("foo.go", strings.NewReader(src))
+			require.Error(t, err)
+		})
+	})
+}
+
 func TestFromAddress(t *testing.T) {
 	as1 := "NQRLhCpAru9BjGsMwk67vdMwmzKMRgsnnN"
 	addr1, err := address.StringToUint160(as1)